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Phylum Arthropoda
Subphylum Crustacea
Class Malacostraca
Order Isopoda
Family Cirolanidae

Bahalana geracei Carpenter, 1981



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Bahalana geracei: after Carpenter, 1981

Taxonomic Characterization: Eyes absent. Body without pigment except for brown mandibular masticatory blades, spines on exopod of maxilla 1, and microscopic crystals surrounding some internal pereional organs. Body is broad (with length three times the width). Unable to roll into a ball. Mandibles asymmetrical. Presence of setation on the endopodites of pleopods 3-5 (Carpenter, 1981).

Disposition of Specimens: National Museum of Natural History, Smithsonian Institution, catalog numbers USNM 172191-3; and Zoological Museum Amsterdam collection number 105.186.

Ecological Classification: Stygobitic

Size: Adult females reach a length of 15 mm, while adult males reach a length of 8 mm.

Number of Species in Genus: Five, all stygobitic

Genus Range:

  • Bahamas:
    • Grand Bahama Island:
      • Lucayan Cavern, Old Freetown Cave, Bahama Cement Cave, plus Janet Pyfrom's, Virgo and Sagittarius Blue Holes and Lucy's and Asgard Caves on adjacent Sweeting's Cay: Bahalana yagerae (Carpenter, 1994)
    • Mayaguana:
    • San Salvador Island:
      • Lighthouse Cave: Bahalana geracei Carpenter, 1981
  • Caicos Islands:

Species Range: Known only from Lighthouse Cave, San Salvador Island, Bahamas.

Closest Related Species: Bahalana cardiopus and Bahalana exumina

Habitat: Anchialine limestone cave

Ecology: Specimens inhabit fully marine waters in an anchialine cave 1 km inland from the coastline. They were observed sitting on the substrate, on top of rocks or upside down under ledges. Occasionally they swim erratically towards the surface of the water and then would return to the substrate. Also found in Lighthouse Cave were: sponges, several species of tube worms, several copepod and ostracod species, the shrimp Barbouria cubensis, a species of asellote isopod, an occasional killifish, bats, cockroaches, snails and one pseudoscorpion species (Carpenter, 1981).

Life History: Females with brood pouches or plates have never been found. Ovaries frequently contain poorly developed eggs and males often have sperm in their sperm ducts. Carpenter (1981) suggests that the production of young is an infrequent event as a mechanism for conserving energy. Females outnumber males by 5 to 1. Bahalana geracei is not gregarious - though cannibalism does occur. Feeding behavior is unpredictable and in the natural habitat, B. geracei probably preys or scavenges on a large variety of aquatic and terrestrial animals.

Evolutionary Origins: The family Cirolanidae is considered the most primitive of the families of the suborder Flabellifera. It is thought that stygobitic cirolanids were stranded when high sea levels receded, either during the Cenozoic Era (55 million years ago) or during the Late Cretaceous Period (135 million years ago) (Carpenter, 1981). All five species in the genus Bahalana are found in the Bahamas archipelago.  Speciation in Bahalana was very probably a rather recent event.

Conservation Status: Restricted to a single cave on San Salvador Island.

References:

  • Carpenter, J.H. 1981. Bahalana geracei n. gen., n. sp., a troglobitic marine cirolanid isopod from Lighthouse Cave, San Salvador Island, Bahamas. Bijdragen tot de Dierkunde, 51(2):259-267, 25 figures.
  • Carpenter, J.H. 1997. Reproduction and population structure of the marine cave isopod Bahalana geracei (Family Cirolanidae) from San Salvador Island, Bahamas. Conservation and Protection of the Biota of Karst, I.D. Sasowsky, D.W. Fong and E.L. White (eds.), Karst Waters Institute Special Publication No. 3.
  • Notenboom, J. 1981. Some new hypogean cirolanid isopod crustaceans from Haiti and Mayaguana (Bahamas). Bijdragen tot de Dierkunde, 51(2):313-331, 9 figures, 2 tables.

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